All locomotives are required by the Federal Railroad Administration to have a parking brake to prevent accidental movement when the locomotive is parked and unattended. Typically, these locomotive parking brakes are manually set by a hand-actuated ratchet lever that tensions a brake chain connected to a wheel brake. The wheel brake is set when the brake chain applies sufficient tension to the wheel brake.
The ratchet lever is normally located at one side of the locomotive and is usually oriented in a vertical position. To reach the ratchet lever an operator must stand on a narrow walkway that runs along the side of the locomotive. In order to actuate the ratchet lever the operator must assume an awkward body position. The ratchet lever must be actuated a number of times in order to obtain the required force of between 175-400 ft.-lbs to set the parking brake. The physical force required to actuate the ratchet lever increases with each stroke as the brake chain is tensioned. Since the operator must assume an awkward body position while actuating the ratchet lever, the potential for strain or sprain injury increases with each stroke of the ratchet lever. The last few strokes of the ratchet lever require a great amount of physical force creating the highest potential for injury. Traditionally, prevention of personal injuries associated with a manual locomotive parking brake has centered around training employees in proper body mechanics and techniques designed to reduce the potential for injury. However, even with employee training, recent studies have shown that such injuries still occur at an unacceptable level.
Another problem that may occur is that, due to the difficulty in setting the locomotive parking brake, some operators may neglect fully setting the brake when the locomotive is left unattended. In addition to the safety problems posed by failing to fully set the brake, such neglect may result in fines or citations from the Federal Railroad Administration.
The present invention solves the above-mentioned problems by providing a powered locomotive parking brake. The locomotive is equipped with a powered drive train that provides the required force of between 175-400 ft.-lbs. to set the parking brake. The powered drive train prevents both the likelihood of injury to the operator and inadequate setting of the parking brake.
Power-assisted parking brakes for automotive vehicles have been known as can be seen, for example, in U.S. Pat. No. 5,178,237. This device comprises a manual brake lever that acts through a Bowden cable to actuate a wheel brake. An electric motor is also connected to the Bowden cable to supply assisting power to set the brake. This device has three modes of operation. These modes of operation include an automatic mode in which the parking brake is set by an electric motor, a power-assist mode in which the electric motor is activated by a manual lever, and a mechanical auxiliary mode in which the brake is set by the manual lever. This device is not acceptable for use to set a locomotive safety brake because of the large amount of force required to set a locomotive safety brake.
A safety stop for a structure that travels along a rail is disclosed in U.S. Pat. No. 1,555,831 in which a motor operates through a series of gears and links to actuate flanges into engagement with the rail. The flanges prevent movement or drifting of the structure caused by wind. A wedge provides an additional stop and is simultaneously moved into engagement with a wheel of the structure to prevent movement.
A brake for a railway train is disclosed in U.S. Pat. No. 1,075,814. The brake of this invention includes a wedge-like member that, when actuated, frictionally engages a wheel of the train and skids along the rail to brake the train. The brake has a flange or flanges that snugly engage the inner faces of the rails to prevent derailment of the car.
A braking system for a rail car is disclosed in U.S. Pat. No. 1.961,010 in which brakes comprising air cylinders are positioned directly in line with the brake shoes to eliminate extra levers and push rods and to obtain quick braking action.
A tractor brake is disclosed in U.S. Pat. No. 3,398,819 in which actuation of the brake causes disengagement of the main clutch and disengagement of the brake causes the main clutch to re-engage.
An electrical control system for brakes is disclosed in U.S. Pat. No. 2,747,693.